Chat can be used in the FL classroom in different ways, including connecting learners located at different sites around the world and bringing an expert into the classroom for learners to interact with virtually. Below are some links to useful sites for setting up chat sessions with your students. (Note: the sites listed below have the benefit of not being commercial and exposing learners to ads or inappropriate content.)
Ideas for using chat in the classroom: CALPER CMC Activity Library
Chat room for in-class activity: Der Bürgermeister ist tot!